A strain tower for T joint and leading-down of a single-circuit overhead transmission line cable comprises a tower body, a ground wire cross arm, an upper layer auxiliary cross arm, middle layer wire cross arms, lower layer auxiliary cross arms, a cable suspension support, cable leading-down terminals shaped like the Chinese character 'bo' and supporting column insulators. The ground wire cross arm is arranged at the top of the tower body, and two lateral cross arms are distributed in the direction perpendicular to the line direction; the upper layer auxiliary cross arm is arranged below the ground wire cross arm, one lateral cross arm is distributed in the direction perpendicular to the line direction, and the tip portion of the upper layer auxiliary cross arm is fixedly provided with the cable leading-down terminals shaped like the Chinese character 'bo' and the supporting column insulators; a strain serial suspension mid-phase wire is fixed to the lower portion of the joint of the upper layer cross arm and the tower body. The strain tower has the advantages that a single-circuit strain T joint and leading-out scheme is disclosed, cable T joint is achieved only with one single-circuit cable T joint strain tower, construction cost is low, occupied area is small, an original line distribution mode is not changed and suitable for construction of tangent towers nearby, and the strain tower can be used.